Ink jet printing is a process in which a stream of ink, preferably in the form of droplets, is ejected at high speed from nozzles against a medium so as to create an image.
Media used for inkjet recording need to be dimensionally stable, absorptive of ink, capable of providing a fixed image and compatible with the imaging materials and hardware. In many instances ink jet printing is carried out on simple paper media particularly in those instances where correspondence and the like is being reproduced.
The typical inks employed in ink jet processes have a fairly high solvent content and the solvents generally include high boiling slow drying polar materials such as glycols, glycol ethers and water. The presence of fairly large amounts of relatively high boiling solvents in the ink can result in the production of an image having a tacky and/or greasy feeling surface.
The recording sheet for an inkjet printer is required to swiftly absorb the ink and have good colour forming properties. To reduce the dry time of the ink it has been previously proposed to provide a recording sheet having a porous layer formed on a substrate, the porous layer being formed of an inorganic oxides such as aluminium oxides or silica.
U.S. Pat. No. 4,517,244 discloses an ink jet recording material having enhanced fixation rates comprising a support having therein a water insoluble resin having a water absorbing capacity of from 50 to 100 times its own weight.
U.S. Pat. No. 5,212,008 discloses a recording sheet which comprises a substrate having two coatings. The first coating comprises (a) a crosslinking agent and (b) a polymer such as a polysaccharide cross linkable by (a). The second coating which is in contact with the first comprises a binder and compound such as an alkoxylated di-fatty quaternary compound.
European Patent Application No 916512 describes a coating fluid for application to a substrate for use in ink jet printing, the coating fluid comprising alumina hydrate particles dispersed in an aqueous medium which contains as binders a polyvinyl alcohol and a polymerisable compound having a hydrocarbon group with a hydroxyl group or a compound having a polyoxyalkylene chain, said compound having a substituent with an unsaturated bond or an epoxy group. The polymerisable compounds disclosed are monomers. The fluid is applied to a substrate such as polyethylene terephthalate, dried and heated with a polymerization initiator to effect polymerization of the polymerizable compound. Compared with the use of polyvinyl alcohol without the polymerizable binder, the advantage stated is that peeling of the coated layer is avoided and good image quality is maintained for a long period of time.
U.S. Pat. No. 5,888,629 describes a medium for ink jet printing which includes a bottom layer of material having a very high absorption for the polar solvent component of the ink jet imaging ink together with a top layer of image receptor material comprising gelatin disposed in fluid communication therewith. The bottom layer which consists essentially of a hydrogel formed from a water insoluble hydrophilic polymer and a water soluble polymer has a very high affinity for the solvent component of the ink and tends to draw the solvent from the body of ink thereby preventing image spread and producing a localized highly saturated image.